Extrusion equipment having means for adjusting a delivery end of a die with respect to the extruder for alignment with downstream equipment

ABSTRACT

In heavy extrusion equipment where alignment with downstream equipment is necessary, adjusters 34 are provided for adjusting the position of the extrusion die (14) with respect to the extruder (12). In practice it is possible to provide a die with a split housing one part of which is adjustable with respect to the other, one of the die parts (14) being fixedly connected to the extruder (12), or by providing a two part die, the parts of which are adjustable with respect to each other. The invention may be utilized for alignment of an extrusion die with downstream equipment such as tooling, tooling dies, sizing tables, etc. and also in corrugations for single and double walled pipe.

FIELD OF THE INVENTION

This invention relates to apparatus for forming elongate thermoplasticsmaterial extrusion especially to apparatus for forming thermoplasticsmaterial profiled pipe such as helically or annularly ribbed orcorrugated pipe. In large extrusion apparatus requiring alignmentbetween the die and downstream equipment, it is conventional to adjustthe position of the extruder carrying the die or the position of thedownstream equipment, or both. The downstream equipment may be, forexample, tooling, tooling dies, sizing tables, etc.

For example, when forming pipe in a mold tunnel, extrudate is extrudedthrough an elongate nozzle of annular cross section into the tunnel toform the pipe. It is very important that the elongate nozzle be axiallyaligned with the tunnel so that even thickness of extrudate is depositedevenly on the walls of the tunnel. This has presented a considerableproblem in the art.

The machinery involved for making pipe of large diameter, say, forexample, a diameter of more than one foot, is very massive. When evenlarger diameter pipe is needed the machinery is even more massive.Nevertheless, it is conventional to align the elongate nozzle either byadjustment of the position of the extruder which carries the die and thenozzle and/or by adjustment of the position of the mold tunnel.

Further problems have occurred in centering a mandrel within an outercasing of the elongate nozzle to ensure that the extrudate itselfemerges having uniform thickness of the wall around its periphery. Thesesubsidiary problems, however, may be approached by providing means forcentering the mandrel within the nozzle casing. It is not thesesubsidiary problems concerning the thickness of the wall of theextrudate which are the concern of the present inventor, but the morebasic problem of properly aligning the nozzle with the mold tunnelwithout the need for adjusting the position of very large pieces ofmachinery.

Conventionally, in order to adjust the relative position of downstreamapparatus with respect to upstream apparatus, it may be necessary tomove the relatively massive upstream apparatus or the relatively massivedownstream apparatus in both lateral and vertical directions. This mayinvolve a large number of adjusting mechanisms all of which must berelatively sophisticated and heavy duty.

In apparatus for making profiled pipe, for example, annularly orhelically ribbed or corrugated double walled pipe, whether the extruderis an in-line feed extruder or a side-feed extruder is an in-line feedextruder or a side-feed extruder, it has been conventional that the diebe fixed in position with respect to the extruder. Thus, it has not beenpossible to adjust the position of the die and elongate extrusion nozzlewith respect to the extruder.

It is possible to provide some minor range of adjustment of theextrusion nozzle casing, i.e. the outer casing of the extrusion nozzlewith respect to the die casing. The purpose of this range of adjustmentis to solve the subsidiary problems referred to above, i.e. to centerthe extrusion nozzle casing around the mandrel which forms the innerwall of a delivery passage for extrudate and thus allow for the deliveryof an extrudate having constant wall thickness. It will be appreciatedthat relative movement between the extrusion nozzle casing and themandrel will affect the wall thickness of the extrudate. Movement of thewhole extruder including the die, the extrusion nozzle and its innermandrel will, however, not affect the adjustment between the extrusionnozzle and its inner mandrel.

For whatever reason, it is wholly conventional in the extrusion art asknown that adjustment of the upstream and downstream equipment involvethe adjustment of the main upstream apparatus and/or the main downstreamapparatus.

The present inventor has addressed the problem which arises inadjustment of the massive extruder and mold tunnels.

Since the die together with the extrusion nozzle casing and itsassociated mandrel is, even when large diameter pipe is to be molded,usually a much smaller part of the apparatus than the extruder or themold tunnel, the present invention contemplates adjustment of theposition of the die together with the extrusion nozzle rather than themold tunnel or the extruder.

BACKGROUND OF THE INVENTION

According to the invention, there is provided apparatus for formingthermoplastics material elongate extrusion comprising an extruder havingan extruder exit passage for extrudate; a die connected to the exitpassage of the extruder through an upstream die position having anupstream portion longitudinal axis; an extrusion nozzle connected to adie downstream portion having a downstream portion longitudinal axis;handling apparatus downstream of the die for handling extrudate emergingfrom the die, the handling apparatus having longitudinal axis inexactlyaxially aligned with the extruder exit passage; the nozzle having anelongate delivery passage for the delivery of extrudate from the die tothe mold tunnel; and means to adjust the position of at least the diedownstream portion with respect to the extruder to provide foradjustment alignment of the die downstream longitudinal axis and thehandling apparatus longitudinal axis.

Also according to the invention, there is provided an apparatus forforming thermoplastics material pipe comprising an extruder having anextruder exit passage for extrudate; a die connected to the extruderexit passage through an upstream die portion having an upstream dieportion longitudinal axis; and elongate extrusion nozzle axiallyalignable with and connected to a die downstream portion having adownstream portion longitudinal axis; a mold tunnel having a tunnellongitudinal axis inexactly axially aligned with the extruder exitpassage; the nozzle having an elongate delivery passage or annular crosssection for the delivery of extrudate from the die to the mold tunnel;and adjustment means to adjust the position of at least the diedownstream portion to correct any deviation from axial alignment withthe mold tunnel. Suitably, apparatus for the manufacture of largediameter pipe may have a die comprising two separate portions, i.e. thedie upstream portion and the die downstream portion. The die upstreamportion is fixed with respect to the extruder and the die downstreamportion is movable with respect to the die upstream portion. Theadjustment means act between the die upstream portion and the diedownstream portion to adjust the longitudinal axis of the die downstreamportion to coincide with that of the mold tunnel. In this case, the diemay have a housing comprising a socket part and a spigot part. Thesocket part may be the upstream portion which is fixed relative to theextruder and the spigot part may be the downstream portion which isadjustable in the socket part to center the longitudinal axis of thespigot portion so that it coincides with the longitudinal axis of themold tunnel.

The inner surface of the elongate passage may be formed by a mandrelcentered axially in the elongate nozzle casing through support meanswhich allows the flow of extrudate through the die. The support meansmay be a spider and may be fixed or adjustable in the die. Suitably, forthe manufacture of large diameter pipe the spider is fixed in thedownstream portion of the die. Any adjustment of the elongate nozzle forthickness of the walls of the extrudate may be made by adjusting theposition of the elongate nozzle casing with respect to the mandrel.

The extruder may be a side-feed extruder or an inline feed extruder. Theadjustment means for adjusting the position of the downstream portion ofthe die casing with respect to the upstream portion of the die casingmay suitably be adjustment screws projecting through the socket wall toadjust the position of the spigot part within it.

Alternatively, the die may comprise a one-piece die. This may be moresuitable for the manufacture of small diameter pipe. In this case, theadjustment means acts between the extruder and the die rather thanbetween two parts of a split die. Again, the adjustment means maycomprise adjustment screws passing through the socket wall of anupstream socket end of the die to adjust it relative to a fixed spigotend of an extruder passage projecting into the socket.

In this case, the inner surface of the elongate passage may again beformed by a mandrel. The mandrel may, as already described, be carriedon a fixed spider. Alternatively, it may be carried on an adjustablespider so that its position within the die may itself be adjustable.There is no special criterion of when an adjustable spider may be usedand when a fixed spider is more suitable. However, it is commented thatthe fixed spider may generally be more suitable for apparatus for themanufacture of large diameter pipe.

SUMMARY OF THE INVENTION

While it is not intended to limit the invention in any way, it may befound that it is particularly suitable for use with apparatus for makingprofiled pipe such as annularly or helically ribbed or corrugated pipe.Apparatus for the manufacture of such pipe has been particularly massivedue to the very large travelling mold tunnels which have conventionallybeen necessary in this art.

BRIEF DESCRIPTION OF THE DRAWINGS

The above as well as other advantages and features of the presentinvention may be described in greater detail according to the preferredembodiments in which;

FIG. 1 is a sketch of a longitudinal section through one apparatusaccording to the invention;

FIG. 2 is a sketch of another apparatus according to the invention;

FIG. 3 is a sketch of yet another embodiment of apparatus according tothe invention;

FIG. 4 is a rough sketch of apparatus according to the inventionincluding a side feed extruder;

FIG. 5 is a line diagram of the axis of the parts of the apparatus ofFIG. 1 and FIG. 3;

FIG. 6 is a line diagram of the axis of the parts of the apparatus ofFIG. 2;

and

FIG. 7 is a line diagram of the axis of the parts of the apparatus ofFIG. 4

DETAILED DESCRIPTION ACCORDING TO THE PREFERRED EMBODIMENTS OF THEPRESENT INVENTION

In the drawings, pipe making apparatus 10 comprises an extruder 12, adie 14 having an extrusion nozzle casing 16 and a mandrel 18, and atravelling mold tunnel 20. The extruder 12 and the travelling moldtunnel 20 are, as is conventional, supported on the floor 22. Ifdesired, the extruder 12 and the travelling mold tunnel 20 may beprovided with adjustment means to bring their longitudinal axis 24 and26 respectively into alignment. However, such adjustment means areconventional and, if present, are only supplementary to any alignmentmeans of the present invention.

The travelling mold tunnel may be of any tube but, as shown, isindicated generally as being a travelling mold tunnel having twoco-operating runs of mold blocks which come together to form the moldtunnel. It will be appreciated at the travelling mold tunnels of otherforms such as those including hinged mold blocks or mold blocks havingreturn mechanisms of other types are equally suitable. Indeed, if thepipe being formed is non-profiled pipe, the mold tunnel need not be ofthe travelling type.

The apparatus illustrated in the drawings may be suitable for themanufacture of profiled pipe such as helically or annularly ribbed pipeor helically or annularly corrugated pipe of either double walled orsingle walled construction. If the pipe to be formed is of the doublewalled variety, modifications will be necessary to the die and to theextrusion nozzle for this purpose. These modifications are conventionaland form no part of the present invention. It is to be understood thatthe present invention may be applied to dies and extrusion nozzlessuitable for the production of all these types of pipe.

FIG. 1 illustrates apparatus suitable for the production of largediameter pipe. The die 14 comprises a housing including an upstreamsocket portion 28 which is supported on a stand 30 on the floor 22. Thedie housing also includes a downstream spigot portion 32 which isadjustable in the socket portion 28 by means of adjusting means 34. Theadjusting means are shown as screws but cams or other equivalent meansmay be used. The adjustment means may be operated automatically by meansof sensors 27 in response to the position of the travelling mold tunnel.The upstream socket portion 28 has a longitudinal axis 36 and thedownstream spigot portion has a longitudinal axis 38. The upstreamsocket portion 28 is fixedly connected to an extruder passage 40 of theextruder 12.

The extrusion passage 40 of the extruder 12 is in line with the generaldirection of flow of extrudate within the die and within the moldtunnel. Mandrel 18 extends upstream from the extrusion nozzle into thedie spigot portion 32 and into the die socket portion 28. As extrudateflows in the cylindrical extrusion passage 40 and into a die entrypassage 42 coincident with it, the upstream end of the mandrel convertsthe die entry passage 42 into an initial annular die passage 44 whichleads into an extrusion nozzle passage 46 which is also annular. Themandrel 18 is supported in the downstream spigot portion 32 of the die14 by means of a fixed spider 48 through the arms of which services,such as cooling fluids or pressurizing fluids may be supplied to thehollow core of mandrel 18 for transport to appropriate utilizationpoints.

The apparatus of FIG. 1 may be roughly assembled so that thelongitudinal axis 24 of the extruder 12, the longitudinal axis 26 of themold tunnel 20 and the longitudinal axis 36, 38 of the die portions aregenerally aligned.

More accurate alignment of the longitudinal axis of the extrusion nozzlewith axis 26 of mold tunnel 20 may be achieved by relative positioningof the socket die portion 28 and the socket spigot portion 32 by meansof adjustment means 34. Thus longitudinal axis 38 of spigot portion 32and the corresponding longitudinal axis of extrusion nozzle casing 16will be aligned with longitudinal axis 26 of mold tunnel 20. Thisaccurate alignment may involve the slight offsetting of die axis 36 and38 with respect to one another. This situation is shown in FIG. 5. Thelongitudinal axis 36 of socket die portion 28 with longitudinal axis 38will however be aligned with the axis of the extruder passage 40. Whenthe axis of extruder passage 40 is not exactly aligned with axis 26 ofmold tunnel 20, there will be an offset (See FIG. 5) between the axis36, 38 of the two parts 28, 32 of the split die. If however the initialsetting up has been extremely accurate, then all the longitudinal axismay be generally aligned. The offset is made possible by means ofadjusting means 34 which adjust the relative positions of the portions28, 32 of the split die casing with respect to one another. In fact, itis only downstream spigot die portion 32 which moves by the action ofthe adjusting screws 34 since upstream socket die portion 28 is fixedwith respect to extruder 12. Since the downstream spigot portion 32carries the extrusion nozzle casing 16 and the mandrel 18 on a fixedspider, any movement of the downstream portion 32 is also transmitted tothe mandrel and to the extrusion nozzle casing.

Means may be provided for relative adjustment between the extrusionnozzle casing and the mandrel 18 by conventional means. For example,adjustment screws 50 may be provided for adjustment of the position ofthe extrusion nozzle casing 16 with respect to the mandrel 18. It shouldhowever be emphasized that this adjustment only affects the dimensionsof the annular extrusion nozzle passage 46. Any adjustment of adjustmentmeans 34 will be transmitted to all of the spigot die portion 32, themandrel 18 and the extrusion nozzle casing 16.

Even when large diameter pipe is to be manufactured the dimensions andweight of the die 14 are small in comparison with those of the extruder12 and the mold tunnel 20. When the die casing is split into two parts28, 32 the size and weight of the movable part is less than that of thewhole die. An advantage may be obtained in the provision of the means ofadjustment of the die or a portion thereof to align the extrusion nozzleof the mold tunnel over the conventional, time consuming, unwieldyprocedures of fine adjustment of the relatively massive extruder or moldtunnel themselves.

It is clear that the fixed portion of the die casing may be the socketportion as shown in FIG. 1 or it may be the spigot portion as shown inFIG. 3. FIG. 3 indicates very similar apparatus to that of FIG. 1 withthe exception that the fixed die casing portion 28 is the spigot portionand stands on stand 30 to be supported by the floor 22. In this case,the movable die portion 32 is the socket portion. Similar referencenumerals are used in FIGS. 1 and 3 to indicate similar parts.

When smaller diameter pipe is to be molded, it may not be necessary toprovide the adjustable die as two separate portions. FIG. 2 showsanother embodiment of apparatus according to the invention in which thedie 14 is not split but comprises a single part. As in FIGS. 1 and 3similar reference numerals are used to indicate similar parts wherepossible. However, in FIG. 2 no parts 28 and 32 are present. The die 14itself is adjustable with respect to extruder passage 40 of extruder 12by means of adjustment means 34. By operation of adjustment means 34,the whole of die 14 in FIG. 2 is movable relative to extruder 12 toadjust the position of its longitudinal axis 114 to coincide with thelongitudinal axis 26 of mold tunnel 20. Any offset 35 will be betweenthe axis of extruder passage 40 and the die axis 114. This is best shownin FIG. 6.

In this case, a further fine adjustment is possible in that anadjustable spider 49 having service line 51 is provided, of the spiderbeing adjustable by means of adjustment screws 52. This makes possibleto adjust the position of mandrel 18 with respect to the longitudinalaxis 114 of die 14 and with respect to the longitudinal axis 26 of moldtunnel 20. Provided that the extrusion nozzle casing 16 is alsoadjustable, for example by means of adjustment screws 50 so that thewidth of annular extrusion channel 46 may be maintained constant, theprovision of the adjustable spider may provide for further fineadjustment.

FIG. 4 shows a sketch of an adjustable die used with a side feedextruder. The use of a side feed extruder does not influence the detailof the invention. The axis 24 of the extruder 12 is not even generallyaligned with the die and tunnel axis but may be at as much as 90° tothem. This is, however immaterial since die part 28 is fixed in relationto the extruder and adjustment of die part 32 alters the position of diepart axis 38 to coincide with tunnel axis 26 (see FIG. 7).

Although various preferred embodiments of the present invention havebeen described herein in detail, it will be appreciated by those skilledin the art, that variations may be made thereto without departing fromthe spirit of the invention or the scope of the appended claims.

What is claimed is:
 1. Apparatus for forming thermoplastics materialelongate extrusion comprising;an extruder having an extruder exitpassage for extrudate; a die having an upstream housing portion and adownstream housing portion, the die being connected to the exit passageof the extruder through the upstream housing portion having an upstreamportion longitudinal axis; an elongate extrusion nozzle connected to thedownstream housing portion which has a downstream portion longitudinalaxis; handling apparatus downstream of the die for handling extrudateemerging from the die, the handling apparatus having a longitudinalaxis; the nozzle having an elongate delivery passage for the delivery ofextrudate from the die to the handling apparatus; and means to adjustthe position of at least the die downstream portion and the elongateextrusion nozzle connected thereto with respect to the extruder toenable alignment of the die downstream longitudinal axis and the nozzlewith the handling apparatus longitudinal axis.
 2. Apparatus for formingthermoplastics material pipe comprising;an extruder having an extruderexit passage for extrudate; a die having an upstream housing portion anda downstream housing portion, the upstream housing portion beingconnected to the exit passage of the extruder and having an upstreamportion longitudinal axis; an elongate extrusion nozzle connected to thedownstream housing portion and having a downstream portion longitudinalaxis; a mold tunnel having a tunnel longitudinal axis; the nozzle havingan elongate delivery passage of annular cross section for the deliveryof extrudate from the die to the mold tunnel; and means to adjust theposition of at least the die downstream portion and the nozzle connectedtherewith with respect to the extruder to enable adjustment alignment ofthe die downstream longitudinal axis and the tunnel longitudinal axis.3. Apparatus as claimed in claim 2, in which the upstream housingportion of the die is fixed with respect to the extruder, the downstreamhousing portion of the die is movable with respect to the upstreamhousing portion, and the adjustment means act between the upstreamhousing portion and the downstream housing portion.
 4. Apparatus asclaimed in claim 3, in which the housing portions of the die comprise asocket part and a spigot part, one part of which is fixed relative tothe extruder and the other of which is adjustable with respect to theone part which is fixed to center the downstream portion longitudinalaxis with the longitudinal axis of the mold tunnel.
 5. Apparatus asclaimed in claim 4, in which said one part is the socket part and saidother part is the spigot part.
 6. Apparatus as claimed in claim 4, inwhich an inner surface of the elongate delivery passage of the nozzle isformed by a mandrel centered axially in the nozzle by support meansallowing flow of extrudate through the die, the support means beingfixed with respect to the downstream housing portion of the die. 7.Apparatus as claimed in claim 4, in which the extruder is an in-lineextruder.
 8. Apparatus as claimed in claim 4, in which the extruder is aside-feed extruder.
 9. Apparatus as claimed in claim 3, in which theadjustment means comprise adjustment screws acting between the upstreamhousing portion and the downstream housing portion of the die. 10.Apparatus as claimed in claim 2, in which the upstream housing portionand downstream housing portion of the die are integral and theadjustment means acts between the extruder and the die.
 11. Apparatus asclaimed in claim 10, in which an inner surface of the elongate passageis formed by a mandrel centerable axially in the elongate nozzle throughsupport means which is adjustable in the die and which allows flow ofextrudate through the die.
 12. Apparatus as claimed in claim 10, inwhich the extruder exit passage is generally aligned with the dieupstream longitudinal axis and the die downstream longitudinal axis.